Treatment of artificial fibrous materials



Feb. 16, 1937. H. DREYFUS 2,070,716

TREATMENT OF ARTIFICIAL FIBROUS MATERIALS Filed Oct. 18, 1932 1- U lvwvdio HENRY DREYFUS AII 5 Patented Feb. 16, 1937 1 UNITED STATESTREATIHENT F ARTIFICIAL FIBROUS MATERIALS Henry Dreyfus, London, EnglandApplication October 18, 1932, Serial No. 638,267 In Great BritainNovember 2, 1931 2 Claims.

This invention, which is a continuation in part of the inventiondescribed in application S. No. 378,684 filed July 16, 1929, relates toimprovements in the treatment of artificial fibrous ma- 5 terial and ismore especially directed to improved processes for effecting thestretching of artificial filaments, yarns, threads, and the like made ofor containing cellulose acetate-or other cellulose esters or ethers, orother varieties of artificial fibres, for example those prepared fromviscose,

cuprammonium and nitro-cellulose spinning solutions.

The stretching of cellulose acetate filaments with resultant increase oftenacity, resistance to hot aqueous media and reduction in denier isfirst described in U. S. PatentNo. 1,709,470. In

U. S. application S. No. 378,684 filed 16th July,

1929, I have described the stretching of artificial filaments, threads,yarns and the like of cellulose acetate or other cellulose esters orethers while the filaments 'are travelling from point to point, forexample from bobbin to bobbin, from beam to beam or from a spinningmachine, e. g. a dry spinning apparatus, to a winding device,

able assisting agents, and particularly solvents or swelling agents forthe cellulose derivative. The said specification describes achieving thestretch by a series of rollers rotated at different peripheral speeds.In this manner the stretch may be inserted in a series of stages. Theimportance of stretching in stages is also described in relation to theinvention of U. S. application S. No. 573,424 filed fithNovember, 1931,which describes the advantages which accrue from allowing a rest periodbetween two or more of the stretching stages. Further, U. S. applicationS. No. 602,844 filed 2nd April, 1932, describes a process for stretchingartificial filaments whilst they are in warp formation.

I have now found that considerableadvantages may be obtained byemploying freely mounted rollers or like devices in conjunction withsuch stretching operations. The rollers may for exthe stretching beingfacilitated by means of suitample be employed as'the means of applyingthe material. If desired the rollers may be provided with grooves inorder to guide the filaments round the periphery of the roller.Suchgrooves have a further advantage as will be hereinafter described.

In employing the freely mounted rollers as the means of applying theassisting agents to the filaments, threads or the like, the latter maybe passed over the rollers which dip into suitable vessels containingthe assisting agent. By employing grooved rollers and by suitableadjustment of the size of the grooves, not only may the filaments orother products be maintained in position, but in addition the amount ofassisting agent supplied to the filaments etc. may be very easilycontrolled, a matter of considerablev importance in the stretching oftravelling filaments, since the amount and uniformity of the stretchobtained depend very largely upon controlling the supply and rate ofsupply of the assisting agent. In addition by applying the assistingagent by means of rollers as described, the rate of travel of thefilaments may be very high, for example to 200 metres per minute ormore, which is of advantage from the economic standpoint and isessential when the stretching is conducted continuously with theproduction of the filaments especially in the case of dry spinning. withsuch high speeds it is desirable that the rollers be of comparativelysmall diameter. As a further modification, the filaments,

threads or the like may be passed under the free- 1y mounted roller orrollers and the latter may then be lowered so as to dip into bathscontaining the assisting agent. By this means relatively sharp angles inthe path of the filaments or other products through the softening bathand to and from the same may be avoided and consequently the-speed oftravel of the filaments or other products may be considerably increasedwithout risk of breakage. Preferably as before, grooved rollers are usedand these may be arranged so that the outer periphery only of the rolleror rollers dips into the softening bath and the softening liquid isdrawn up into the groove. The filaments or the like are led under therollers and in the grooves thereof so that they do not actually contactwith the main softening bath and thus take up anamount of softeningliquid controlled in accordance with the dimensions of the grooves.

The invention further includes inserting the stretch by means of aseries of the freely mounted rollers or similar devices into which thefilaments, threads, yarns etc. are brought into subare immersed in theliquid. The rotatio stantially non-slippin contact, the resistance torotation of which gives rise to the tension necessary to stretch thefilaments or other products. The advantages attaching to stretching instages are thus obtained to an enhanced degree. The process ofstretching, which makes use of the resistance to rotation of the rollersmay be applied continuously with the production of artificial filaments,and by this means the stretch may be wholly or partially prevented fromrunning back to the jet from which the filaments are extruded.

The amount of stretch inserted between any two rollers is dependent upontheir resistance to rotation and such resistance may be controlled tionof the rollers is increased. Thus for example the rollers may be causedto run in contact with a liquid which may be more or less viscous, or avane or similar device may be attached to each 'roller and this vaneexposed to the fluid drag exerted by a gaseous or liquid medium. A Jet"ofair or other gas may be .caused to play upon a vane or like device insuch a manner as to tend to set up a rotation in the reverse directionto that'brought about by the filaments themselves, or the vane may bedisposed in a substantially closed compartment so that the air orgaseous medium tends to retard the rate of rotation. The retardation maybe controlled in these cases by theuse of jets of air or other gas"ofvarying intensity or by the use of liquids having varyingviscosities. Instead of the vane rotating wholly in a liquid, it may beso disposed that it dips only partially into the liquid. Theretardationof the roller may then easily be controlled by varying the depth towhich the vanes 01' the roller may also be retarded by an electr-magnetic device or by any other suitable device. In that form of theapparatus in which vanes attached "to the rollers rotate in a liquidmedium, thebath of assisting agent may be used as the liquid medium. Ifdesired the vanes may be provided in this process with a coveringshield. Such a shield will serve to increase the drag on the roller andwill localize in the bath the disturbance c'aused'by the rotating vanes.

Where the freely mounted rollers assist in the stretching operation thefilaments, yarns, threads and the like should be carried intosubstantially non-slipping contact with the series of freely mountedrollers or like devices, for example by carrying the filamentscompletely round the rollers. By applying a tension to the filamentsafter contact with the series of rollers the stretch is impartedthereto. For example at the end of a series of ,rollers a driven feedroller or like device may be employed, or alternatively feed rollers maybe inserted at intervals along a series of the freely mounted rollerscharacteristic of the invention. Where the freely mounted rollers offeronly a comparatively small resistance to rotation a very long series ofsuch rollers may be employed with the result that the stretch isimparted to the filaments very gradually indeed. Alternatively if theresistance to rotation of the freely mounted rollers is substantial arelatively limited number of rollers maybe used, but still theadvantages accurlng from stretching in stages are obtained. 1

1 For treating filaments of cellulose acetate or other organic esters orethers of cellulose, suitable assisting agents are acetic acid, formicacid, lactic acid, diacetone alcohol, acetone and the like; the ethers,esters and ether-esters of olefine and polyolefine glycols, for instancethe monoand di-methyl and ethyl ethers of ethylchloride, methyl acetateand ethyl acetate. Such solvents or swelling agents may be diluted withwater or with organic non-solvents, for

instance hydrocarbons, alcohols or ethers.

The solvents or swelling agents may be applied before or during thestretching operation of the invention.

Where the solvent or swelling agent is applied during the stretchingoperation, the tension applied to bring about the stretch may berestricted to the softened portion of the thread,

and wholly or partially be prevented from running back to that portionof the threadwhich has not reached the optimum condition for stretching.a

Afterstretching in accordance with the present invention the solventor'swelling' agent may either be allowed to dry in the filaments orthreads or it may be washed off before drying. When as is mostefitective the solvent or swelling agent is applied in relatively highconcentration, it is desirable to take precautions in the removal, sincea too rapid removal tends to impair the lustre of the filaments or otherproducts. For this purpose the filaments, instead of beingwashed'directly with water to remove the solvent, may be treated withsalt solutions may afterwards he carried out while maintaining thefilments or threads undertension or in the absence of tension.

If desired the filaments, threads, yarns and the like treated accordingto the present invention may be submitted to a shrinking operation inorder to modify their properties, e. g. their extension, as describedfor example in U. S. application S. No. 611,240 filed 13th May, 1932.Suitable apparatus for use in this invention is shown in the drawing,but it is not to be considered as limiting the invention-in any way.Figure 1 shows an elevation of a suitably grooved roller provided withvanes dipping into a bath of assisting agent.

Figure 2 shows a method of attaching vanes to the roller so that theymay be adjusted. Figure 3 shows a suitable form of apparatus forstretching the filaments or threads whilst groove 2 which may be of anydesired depth is arranged so that onlythe outer periphery of the rolleris immersed in the bath of assisting agent 3. The roller is providedwith vanes I 76 which are partially immersed in the liquid of the bath.Shields 5 serve to prevent the rotating vanes causing turbulence in theliquid near the grooved roller.

In the method of attaching vanes so that they may be adjusted shown inFigure 2, the vanes 6 are pivotally mounted on the roller 1. The pivot 8is of such construction that the vanes may be disposed in a planeparallel to the axis of the roller, or in a plane making any suitableangle with the axis.

In Figure 3 filaments, threads or the like I3 are led from a bobbin orother package to a feed roller '9 and thence to a freely mounted rollerI dipping into a bath of assisting agent II. A third roller l2 rotatingat a greater peripheral speed than the feed roller 9 exerts a stretchingaction on the filaments or the like, and the filaments are then washed,dried, and wound, or twisted and wound.

In Figure 4 the filaments l3 issuing from a dry-spinning cell are ledround a. feed roller 14 and under the freely mounted grooved rollers l5.Other freely mounted rollers l6 are arranged alternately with therollers l5, and these are connected together by a structure I! which maybe adjusted to any height by any suitable raising or lowering mechanism(not shown). By adjusting the height of the rollers It the tension onthe filaments or threads may be, controlled. Alternatively, the freelymounted rollers I 6 may be arranged to be adjusted independently, andthus by raising them by different amounts the amount of lap onindividual grooved rollers may be varied. Thus little or no stretch maybe effected while passing over certain of the rollers, e. g. the earlierones, while with others, e. g. later ones, stretching may be carriedout. The mounted rollers l are so disposed that only their outerperipheries are immersed in the liquid contained in the bath l8. Therollers I5 may also be provided with means opposing their tendency torotate under the action of the filaments, such as the vanes shown inFigures 1 or 2. The filaments, after leaving the bath l8 are led to aspray washing device l9 and then to a winding device 20. The distancebetween the washing device I 9 and the winding device 20 may besumciently great for the filaments to dry, or a drying device may beinterposed between these two devices, or the filaments or threads may bewound in the wet condition.

The present invention may also be adapted to produce effect filaments orthreads. Thus for example by using rollers which are grooved axiallyinstead of circumferentially softening agent may be applied inanon-uniform manner, and filaments'thus treated will exhibit afterstretching, a variable denier along their length.

As already indicated the invention is of the greatest value in itsapplication to the stretching of filaments, threads and the like ofcellulose acetate or other organic derivatives of cellulose, for examplecellulose formate, cellulose propionate, cellulose butyrate, cellulosenitroacetate or other organic esters of cellulose, cellulose nitrate, orcellulose ethers, or mixed ethers, e. g. ethyl, butyl or benzylcellulose, and mixed ether-esters, e. g. ethyl cellulose acetate andoxyethyl cellulose acetate. However, the invention may also be appliedto the stretching of other filaments, for example those produced by thecuprammonium, viscose and nitrocellulose processes, and consistingsubstantially of cellulose. Swelling agents for use with such materialscomprise, for example, thiocyanates, caustic alkalies, and Schweitzersreagent.

What I claim and desire to secure by Letters Patent is:-

1. In a process wherein filaments, threads, yarns and like materialhaving an organic derivative of cellulose base are softened, the stepsof causing said materials to run below and in nearly tangential contactwith the root of a peripheral groove in a cylindrical surface adapted tobe rotated about its longitudinal axis by said materials, andmaintaining a body of softening liquid for the base of said materials insuch a position that its surface is below the lowest point of the rootof said groove but above the lowest point of the peripheral edges ofsaid groove, whereby said groove is kept supplied with softening liquid,the main body of softening liquid being kept out of contact with thematerials.

2. In a process wherein filaments, threads,

yarns and like materials having an organic derivative of cellulose baseare softened, and stretched while in the softened condition, the stepsof causing said materials to run below and in contact with the root of aperipheral groove in a cylindrical surface adapted to be rotated aboutits longitudinal axis by said materials, maintaining a body of softeningliquid for the base of said materials in such a position that itssurface is below the lowest point of the root of said groove but abovethe lowest point of the peripheral edges of said groove, whereby saidgroove is kept supplied with softening liquid, the main. body ofsoftening liquid being kept out of contact with the materials, andretarding the rotation of said cylindrical surface.

HENRY DREYFUS.

